Liverpool scientists are behind a potentially revolutionary breath test designed to detect the early signs of lung cancer.

The test was developed after scientists discovered subtle genetic changes in vapour given off by cells which may help shape the way lung cancer – the biggest cause of cancer death in the UK each year – is detected.

Researchers from the Roy Castle programme at the University of Liverpool and the Technion-Israel Institute of Technology examined cells taken from the lining of airways that had been engineered to carry different genetic faults linked to early stage lung cancer.

They developed a technique for analysing the vapour inside the container in which the cells were growing and showed it was capable of distinguishing which of the two different genes were faulty in the cells. The disease kills more than 35,000 annually in the UK, and has a low survival rate because diagnosis is often at the terminal stage.

Dr Mike Davies, from the Roy Castle Lung Cancer Research Programme, said: “These findings tell us that it’s theoretically possible to develop a test that could diagnose early lung cancer in the breath of patients.

“There’s an urgent need to diagnose lung cancers earlier, when treatment is more effective.

“This is a potential step towards developing a handheld device that could aid lung cancer screening and diagnosis. It could also be used to help match patients to the right treatment by providing doctors with a snapshot of the genetic make-up of their individual tumour.”

He said tests would be carried out on cancer patients to see whether the method can accurately diagnose genetic changes in growing lung tumours.

“But we’re still a way off from the large-scale trials necessary before this technique could be used widely.

“Lung cancer is extremely difficult to treat, but when diagnosed at its earliest stage, around 70% of patients will survive their disease for a year or more, compared with 14% when the disease is diagnosed at its most advanced stage.

“So, any test that could potentially diagnose the disease earlier would be good news for patients. In the meantime, anyone with a persistent cough, shortness of breath or blood in their phlegm should see their GP as soon as possible.”